Bed monitoring system

ABSTRACT

A bed monitoring system ( 1 ) includes a substantially rectangular bed ( 2 ) for supporting a user (not shown). Bed ( 2 ) is longitudinally extending between a bed head and a bed foot and has a periphery that is crossed by the user to move from the bed. Three spaced apart sensors, in the form of respective photo-electric receivers ( 6, 7  and  8 ), are mounted to bed ( 2 ) and are collectively responsive to the user crossing the periphery for generating a movement signal. Three generators, in the form of spaced apart photoelectric emitters ( 9, 10  and  11 ), are mounted to bed ( 2 ) for establishing a field in the form of respective beams ( 12, 13  and  14 ). These beams are detected by receivers ( 6, 7  and  8  respectively), and are changed by the user crossing the periphery along which the respective beam extends. Emitters ( 9, 10  and  11 ) are contained within a common housing with receivers ( 6, 7  and  8 ) respectively.

FIELD OF THE INVENTION

The present invention relates to a monitoring system and in particular to a bed monitoring system.

The invention has been developed primarily for beds in nursing homes that cater to frail and mentally ill patients, and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use and is also suitable for other beds whether in nursing homes or other sites.

BACKGROUND OF THE INVENTION

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Due to economic practicalities and the costs of personal medical care in nursing homes, care-givers, such as nurses and other medical staff, often are responsible for many patients at any one time. As a result, the activities and whereabouts of all the patients cannot be continually monitored.

This is particularly awkward for patients who are weak, frail and/or mentally incompetent as they often attempt to leave or enter their beds without assistance. As a result, there is increased risk of injury to the patients and an increased risk of liability for the nursing home.

A partial solution to this problem is disclosed in PCT Patent Application PCT/US96/12212. More particularly, use is made of two parallel and longitudinally spaced apart pressure sensitive sensor strips that extend transversely across the bed. The strips are intended to allow detection of whether or not the patient is still in the bed. However, the strips permit a lot of patient movement before providing any indication that the patient is actually attempting to leave their bed. Moreover, such an arrangement is easily circumvented through the use of a dummy weight.

Another partial solution to this problem is the use of ultra sonic sound waves to monitor an area in and around the bed. However, this solution is inaccurate and results in a large number of false alarms. A patient moving or sitting up within their bed or a person walking past the bed can easily interrupt the field and cause a false alarm. This results in an increased workload and wasted time for the care-givers.

Another possible solution involves the use of an ultrasonic emitter and sensor combination that detects for the presence on the bed of the patient. Such systems are typically very difficult to accurately calibrate, and are extremely sensitive to environmental changes over time, such as temperature changes, movement of objects other than the patient, and the like.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

According to a first aspect of the invention there is provided a bed monitoring system including:

a bed for supporting a user, the bed having a periphery that is crossed by the user to move from the bed; and

at least one sensor that is mounted to the bed and which is responsive to the user crossing the periphery for generating a movement signal.

Preferably, the system includes a controller being responsive to the movement signal for generating an alert signal. More preferably, the system includes a least one generator mounted to the bed for establishing a field that is detected by the sensor and which is changed by the user crossing the periphery. Even more preferably, the generator is a source of electromagnetic radiation and the sensor is a photoelectric device that is responsive to the radiation.

Preferably also, the system includes at least one reflector mounted to the bed to reflect electromagnetic radiation from the generator to the sensor.

In a preferred form, the generator emits radiation of a wavelength that is visible to the human eye. However, in other embodiments, the generator emits radiation of a wavelength that is invisible to the human eye. In further embodiments, the generator emits a combination of radiation, some being of a wavelength that is visible to the human eye and some being of a wavelength that is invisible to the human eye.

Preferably, the system includes an alarm system that is responsive to the alert signal. More preferably, the alarm system is a medical staff-call system. More preferably, the alarm system includes an audible and/or visible alarm.

According to a second aspect of the invention there is provided a monitoring system for a bed having a periphery that is crossed by the user to move from the bed, the system including:

a generator that is mountable to the bed for providing a field that extends along the periphery;

at least one sensor that is mountable to the bed, the sensor being responsive to a change in the field caused by the user crossing the periphery for generating a movement signal.

According to a third aspect of the invention there is provided a method of monitoring a bed, the method including:

providing a bed for supporting a user, the bed having a periphery that is crossed by the user to move from the bed;

maintaining the bed a given distance above a predetermined datum with a support device that extends from the bed; and

mounting at least one sensor to the bed for responding to the user crossing the periphery for generating a movement signal.

According to a fourth aspect of the invention there is provided a method of monitoring a bed having a periphery that is crossed by the user to move from the bed, the method including:

mounting a generator to the bed for providing a field that extends along the periphery; and

mounting at least one sensor to the bed, the sensor being responsive to a change in the field caused by the user crossing the periphery for generating a movement signal.

According to a fifth aspect of the invention there is provided a sensor assembly for a bed, the assembly including:

a support member for mounting to the bed;

at least one sensor support that extends between a proximal end that is mounted to the support member and a distal end, wherein the support is movable between an operable position and a stored position in which the distal end is respectively spaced apart from and adjacent to the member; and

sensor equipment that is mounted at or adjacent to the distal end.

Preferably, the support member is releaseably mounted to the bed. More preferably, the support member is clampingly mounted to the bed.

Preferably also, the assembly includes two sensor supports that are at or adjacent the ends of the member. More preferably, the distal ends of the respective supports progress toward each other as they are moved into the stored position.

In a preferred form, the support is gravitationally biased into the operable position. More preferably, the member includes a locating formation, and the proximal end includes a mounting formation that inter-engages with the locating formation for guiding the movement between the operable and the stored positions. Even more preferably, the locating formation includes a pair of opposed flanges and a locating pin, and the mounting formation includes a slot for slideably receiving the pin.

Preferably, during movement between the operable and stored positions, the locating formation and the mounting formation are relatively translated and rotated. More preferably, the translation and rotation are consecutive. More preferably, there is only a single translation and a single rotation.

Preferably also, the proximal end is slideably mounted to the member. More preferably, the member extends transversely, and the support is mounted to the member for relative slidable movement between the operable and the stored positions. Even more preferably, the member is tubular and the support is telescopically mounted within the member.

In a preferred form, the sensor support includes an arm that is moveable between a nested and an extended configuration with respect to the support member in response to predetermined movement of the sensor support toward the retracted and operable positions respectively. More preferably, the sensor assembly includes a locking device that moves between a locked and an unlocked configuration wherein, in the locked configuration, the locking device maintains the arm in the extended position. Even more preferably, the locking device automatically moves to the locked configuration as the arm moves into the extended configuration. Preferably also, the locking device is manually moved into the unlocked configuration.

According to a sixth aspect of the invention there is provided a method of mounting a sensor assembly to a bed, the method including:

mounting a support member to the bed;

providing at least one sensor support that extends between a proximal end that is mounted to the support member and a distal end, wherein the support is movable between an operable position and a stored position in which the distal end is respectively spaced apart from and adjacent to the member; and

mounting sensor equipment at or adjacent to the distal end.

According to a seventh aspect of the invention there is provided a method of assessing the future assistance required by a user who is to be contained, during a predetermined period, to a bed, the method including:

mounting to the bed a monitoring system according to the second aspect of the invention;

being responsive to the movement signal for alerting a care-giver to movement of the user from the bed;

recording time stamp data for each occurrence of the movement signal in the predetermined period; and

being responsive to the time stamp data for assessing the future assistance required by the user.

According to an eighth aspect of the invention there is provided a method of monitoring a user who is to be contained, during a predetermined period, to a bed, the method including:

mounting to the bed a monitoring system according to the second aspect of the invention;

being responsive to the movement signal for alerting a care-giver to movement of the user from the bed; and

recording time stamp data for each occurrence of the movement signal in the predetermined period.

Preferably, the time stamp data includes an identifier for the predetermined period. More preferably, the time stamp data is gathered over a plurality of predetermined periods.

Preferably also, the method includes the step of being responsive to the time stamp data for providing a report of instances where the user has moved from the bed.

In a preferred form, the bed is provided by a health care establishment, and the user pays a fee to the health care establishment to occupy the bed. More preferably, the method includes the step of being responsive to the report for generating the fee.

According to a ninth aspect of the invention there is provided a monitoring system for a bed having a periphery that is crossed by the user to move from the bed, the system including:

a generator that is mountable to the bed for providing a field that extends along the periphery;

at least one sensor that is mountable to the bed, the sensor being responsive to a change in the field caused by the user crossing the periphery for generating a movement signal; and

a display that is mountable to the bed and which is responsive to the movement signal for providing a visual alarm.

Preferably, the visual alarm is primarily directed away from the user. More preferably, the visual alarm is primarily directed upwardly.

Preferably also, the system includes a housing, wherein the display is mounted in or to the housing. More preferably, the housing includes a surface to which the display is mounted. In a preferred form, the surface is upwardly facing.

According to a tenth aspect of the invention there is provided a monitoring system for a bed having a periphery that is crossed by the user to move from the bed, the system including:

a generator that is mountable to the bed for providing a field that extends along the periphery, wherein the periphery is substantially planar;

at least one sensor that is mountable to the bed, the sensor being responsive to a change in the field caused by the user crossing the periphery for generating a movement signal; and

a housing for containing one or both of the generator and the sensor, the housing having a depth parallel to the field, and a height and width normal to the field, wherein, in use, the height is less than the width.

Preferably, the height is substantially less than the width. More preferably, the height is less than 25% of the width.

According to an eleventh aspect of the invention there is provided a method for monitoring a bed having a periphery that is crossed by the user to move from the bed, the method including:

mounting a generator to the bed for providing a field that extends along the periphery;

mounting at least one sensor to the bed, the sensor being responsive to a change in the field caused by the user crossing the periphery for generating a movement signal; and

mounting a display to the bed and which is responsive to the movement signal for providing a visual alarm.

According to a twelfth aspect of the invention there is provided a method for monitoring a bed having a periphery that is crossed by the user to move from the bed, the method including:

mounting a generator to the bed for providing a field that extends along the periphery, wherein the periphery is substantially planar;

mounting at least one sensor to the bed, the sensor being responsive to a change in the field caused by the user crossing the periphery for generating a movement signal; and

containing within a housing one or both of the generator and the sensor, the housing having a depth parallel to the field, and a height and width normal to the field, wherein, in use, the height is less than the width.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a side view of a first embodiment of a bed monitoring system according to the invention;

FIG. 2 is a plan view of the bed monitoring system of FIG. 1;

FIG. 3 is front view of a mounting frame of the system of FIG. 1 that is adapted for engagement with the head of the bed;

FIG. 4 is a plan view of the mounting frame of FIG. 3;

FIG. 5 is a perspective view of another mounting frame of the system of FIG. 1 that is adapted for engagement with the foot of the bed;

FIG. 6 schematically illustrates the interconnection of the system of FIG. 1 with a medical staff-call system;

FIG. 7 is a circuit diagram for the controller shown in FIG. 6;

FIG. 8 is a schematic perspective view of the bed monitoring system of FIG. 1 when mounted to the bed;

FIG. 9 is a perspective view of a second embodiment of a bed monitoring system according to the invention;

FIG. 10 is a front view of a mounting frame of the system of FIG. 9 that is adapted for mounting to the foot end of the bed;

FIG. 11 is a perspective view of one of the side arms of the mounting frame of FIG. 10;

FIG. 12 is a perspective view of the other side arm or the mounting frame of FIG. 10;

FIG. 13 is an exploded view of the mounting for the emitter and receiver pairs of FIG. 11;

FIG. 14 is an exploded view of the mounting for the emitter and receiver pair of FIG. 12;

FIG. 15 is a plan view of another mounting frame of the system of FIG. 9 that is adapted for mounting to the head end of the bed;

FIG. 16 is a rear view of an arm of the mounting frame of FIG. 15;

FIG. 17 is an end view of the arm of FIG. 16;

FIG. 17 is a partial front view of a support member of the mounting frame of FIG. 15;

FIG. 19 is an end view of the member of FIG. 16; and

FIG. 20 is a perspective view of a housing for the electronic circuitry mounted to the assembly of FIG. 15;

FIG. 21 is a rear view of the housing of FIG. 20;

FIG. 22 is a side view of the housing of FIG. 20;

FIG. 23 is another side view of the housing of FIG. 20;

FIG. 24 is an underside view of the housing of FIG. 20;

FIG. 25 is a perspective view of a third embodiment of a bed monitoring system according to the invention;

FIG. 26 is a cutaway side view of the foot of the bed in FIG. 25;

FIG. 27 is an exploded side view of one of the mounting frames of FIG. 25;

FIG. 28 a cut-away side view of that portion of the mounting frame of FIG. 27 that engages the bed;

FIG. 29 is a top view of the portion of the mounting frame of FIG. 28;

FIG. 30 is a side view of an arm of the mounting frame of FIG. 27;

FIG. 30( a) is an end view of the arm of FIG. 30;

FIG. 31 is a side view of a turntable of FIG. 27;

FIG. 31( a) is a top view of the turntable of FIG. 31;

FIG. 32 is an exploded perspective view of a housing for the electronic circuitry mounted to the assembly of FIG. 25;

FIG. 33 is a cut-away side view of the third mounting frame of FIG. 25;

FIG. 34 is top view of the mounting frame of FIG. 33;

FIG. 35 is a perspective view of the mounting frame of FIG. 33;

FIG. 36 is a schematic diagram of the electronic circuitry of FIG. 25; and

FIG. 37 is a schematic diagram of the PC Board containing the electronic circuitry of FIG. 25.

PREFERRED EMBODIMENT OF THE INVENTION

Referring to FIG. 1 and FIG. 2, there is illustrated a first embodiment of a bed monitoring system 1. System 1 includes a substantially rectangular bed 2 for supporting a user (not shown). As best shown in FIG. 2, the bed is longitudinally extending between a bed head and a bed foot—as will be described below in more detail—and has a periphery that is crossed by the user to move from the bed. Three spaced apart sensors, in the form of respective photo-electric receivers 6, 7 and 8, are mounted to bed 2 and are collectively responsive to the user crossing the periphery for generating a movement signal.

Three generators, in the form of spaced apart photoelectric emitters 9, 10 and 11, are mounted to bed 2 for establishing a field in the form of respective beams 12, 13 and 14. These beams are detected by receivers 6, 7 and 8 respectively, and are changed—that is, by one or more of the beams being broken—by the user crossing the periphery along which the respective beam extends. Emitters 9, 10 and 11 are contained within a common housing with receivers 6, 7 and 8 respectively. In this embodiment, the emitter and receiver pairs are each comprised of a retro-reflective sensor, such as that manufactured by Banner Engineering Corporation and branded as “World Beam Polarised Retroreflective QS18VP6LP”. This retro-reflective sensor operates at or about the visible red light wavelength of 660 nm. In other embodiments, different retro-reflective sensors are used, and operate at other wavelengths.

In other embodiments, use is made of alternative generators and corresponding sensors. For example, in one embodiment, use is made of an ultrasonic generator and sensor, while in another embodiment use is made of a low power laser generator and detector. In further embodiments, the generator produces a field of visible light, while in another embodiment, the generator produces a field of light that is not visible to the human eye. In still further embodiments, the field provided by the generator is made from a combination or a range of frequencies of electromagnetic radiation.

Preferably, the emitter and receiver pairs are not only constituted by a retro-reflective sensor, as described above, but by a polarised retro-reflective sensor, as this minimises errors arising from light from unwanted sources. The sensing range of the receiver within the preferred retro-reflective sensor is centred with the spectrum of the signal provided by the respective emitter.

Three generally square spaced apart reflectors 15, 16 and 17 are mounted to bed 2 and opposed with emitters 9, 10 and 11 to reflect beams 12, 13 and 14 back toward respective receivers 6, 7 and 8. Each reflector provides a retro-reflective target, and consists of a matrix of tiny corner-cube prisms. Each prism has three mutually perpendicular surfaces and a hypotenuse face. The respective light beams enter a corner-cube prism through its hypotenuse face and is reflected from the three surfaces to emerge back through the hypotenuse face, parallel to the entering beam. This redirects the beam back along itself and to the source.

In this embodiment, the corner-cube reflector is 50 mm square and made of transparent acrylic plastic. As a retro-reflector, such as that disclosed, is able to return incident light that has an angle of incidence of greater than about 70°. Consequently, system 1 is relatively insensitive to the alignment of the reflectors, and easily accommodates the typical mechanical disturbances that are experienced by a hospital or other patient bed. Additionally, this allows system 1 to be positioned and operated without highly skilled technicians having to calibrate the alignment or, in the event of a disturbance, re-calibrate the alignment.

In other embodiments, alternative reflectors are used. In further embodiments, reflectors are not used but, rather, the sensor and generator pairs are spaced apart at opposite ends of the respective fields.

Bed 2 includes a substantially planar and horizontal metal base 18 that extends longitudinally between a head end 19 to a foot end 20. Ends 19 and 20 of base 18 are adjoined by transversely extending sides 23 and 24. A bed head 25 is connected to end 19 and extends normally from base 18 between a top edge 26 and a pair of opposed and transversely spaced apart legs 27. A footboard 28 is connected to end 20 and extends normally from base 18 between a top 29 and a pair of opposed and transversely spaced apart legs 30.

Base 18 supports a mattress 31 that lies within ends 19 and 20 and sides 23 and 24.

The periphery of bed 2 is defined collectively by beams 12, 13 and 14 which are, as best shown in FIG. 2, not directly superimposed above side 23, end 20 and side 24 respectively. That is, beams 12 and 14, while being substantially horizontally coplanar, are angled toward each other such that they intersect vertical planes that extend through respective sides 21 and 22. Beam 13, however, is parallel to end 20, although slightly transversely offset from it. In other embodiments, the beams are directly superimposed with the respective edges. In other embodiments, the beams are more closely aligned with the sides and ends of the bed.

The vertical displacement between the top of mattress 31 and beams 12, 13 and 14 is about 150 mm. In other embodiments, alternative displacements are used. Moreover, in some embodiments, beams 12 and 14 are inclined with respect to the horizontal. Preferably, that inclination is such that the beams are inclined downwardly from end 19 to end 20. That is, the lower point of the beam is at the foot end 20.

In this embodiment, the field is composed of beams that are narrow and substantially circular in cross section. However, in alternative embodiments, other cross sectional shapes are used, while in other alternative embodiments, one or more of the beams is vertically elongate. That is, in some embodiments, the field is in the form of a “sheet” of radiation that extends vertically or which is inclined with respect to the vertical.

The creation of the field—through the placement of the beams—is such that it will be respectively broken by a person attempting to move from the bed. Accordingly, there is not a need for exact correspondence between the edges of the bed and the beams. In fact, in some embodiments, the beams are spaced further from the bed than is described above. This occurs, for example, with those patients who are known to move of thrash about considerably within the bed without actually moving from the bed. The additional spacing of the beams from the edges and end of the bed reduce the risk of a false movement signal being produced—that is, when the person is simply moving on the bed—while still allowing the correct provision of the movement signal if there is a movement of the person from the bed.

The field provided by the beams 12, 13 and 14 is not continuous but, rather segmented. However, the distance between the segments is either sufficiently small for a person to pass through or, in the case of discontinuity at the head of the bed, in an area where it is extremely unlikely that the person could progress through to move from the bed. In another embodiment (not illustrated) the field is continuous. For example, where use is made of a single generator and reflector pair, and where the resultant field is composed of a beam of electromagnetic radiation that is redirected about the periphery by a plurality of spaced apart reflectors.

System 1 includes a mounting frame 34 that is illustrated in more detail in FIG. 3 and FIG. 4. This frame allows positioning of system 1 with respect to the bed to allow the desired beam orientation to be achieved. Particularly, frame 34 includes two spaced apart coaxial 25 mm×25 mm×1 mm RHS tubular beams 35 and 36. Beam 35 extends substantially horizontally from a first end 37 to a second end 38 that are spaced apart by about 350 mm. The beam includes a substantially vertical front face 39 and an opposite back face 40 that both extend between the ends and which are joined by substantially horizontal top and bottom faces 41 and 42. A 1.6 mm thick galvanised iron mounting bracket 43 extends forwardly and upwardly from face 39 for providing support to an electronic controller 44 that is shown in FIGS. 1 and 2, and discussed further below with reference to FIG. 6.

Beam 35 also includes a cylindrical steel post 45 that extends downwardly from face 42 and terminates in a free end 46. Post 45 provides support to a carriage 47 that is rotatably and slideably mounted to the post for selective movement between a raised and a lowered configuration. The carriage is selectively maintained in a fixed configuration with respect to post 45 by manual operation of a grub screw (not shown).

Receiver 6 and emitter 9 are mounted to an arm 48 that is, in turn, rotatably connected to carriage 47. This allows infinite relative spatial adjustability between the receiver and emitter pair and the corresponding reflector 15. That is, the pan and tilt of the emitter and receiver pair is adjustable, as is its relative height with respect to bed 2 and therefore with respect to the relevant retro-reflector. With this degree of adjustability built into system 1, it is able to be mounted selectively to many types of beds without requiring dedicated configuration.

While some embodiments of the invention are designed specifically for a particular bed, system 1 is designed for retro-fitting to one of a range of beds.

Beam 35 also includes a retaining formation in the form of a metal bracket 49 that is mounted to and which extends rearwardly from face 40. The bracket defines an engagement face 50 and an opening 51 for receiving an object to be brought into engagement with face 50.

Beam 36 extends substantially horizontally from a first end 52 to a second end 53 that are spaced apart by about 300 mm. This beam includes a substantially vertical front face 54 and an opposite back face 55. These faces extend between ends 52 and 53 and are joined by substantially horizontal top and bottom faces 56 and 57.

Beam 36 also includes a cylindrical steel post 58 that extends downwardly from face 57 in parallel with post 45 and terminates in a free end 59. Post 58 provides support to a carriage 60 that is rotatably and slideably mounted to post 58 for selective movement between a raised and a lowered configuration. Receiver 8 and emitter 11 are mounted to an arm 61, which is rotatably connected to carriage 60. This allows infinite relative spatial adjustability between the receiver and emitter pair and the corresponding reflector 17, as is the case with the above described with reference to the emitter and receiver pair mounted to carriage 47.

Beam 36 also includes a retaining formation in the form of a steel bracket 62 that is mounted to and which extends rearwardly from face 55. The bracket defines an engagement face 63 and an opening 64 for receiving an object to be brought into engagement with face 63.

Frame 34 includes a third intermediate 22 mm×22 mm×1 mm RHS tubular beam 65 having two opposite ends (not shown) that are respectively received within ends 38 and 53 for allowing relative transverse telescopic progression of beam 65 with each of beams 35 and 36. This progression is prevented by manually turning one or both of thumb wheels 66 and 67 to move corresponding grub screws (not shown) into a locked configuration. Conversely, the progression is allowed by manually turning the one or both of wheels 66 and 67 to move the corresponding grub screws into an unlocked configuration.

Frame 34, in use, is releasably mounted to bed head 25. This initially includes manually turning one or both of wheels 66 and 67 to move the corresponding grub screws into an unlocked configuration. Frame 34 is then extended by telescopically progressing at least one, and preferably both of beams 35 and 36 along beam 65 to increase the transverse spacing between brackets 49 and 62. The frame is then positioned adjacent to bed head 25 such that ends 40 and 55 of respective beams 35 and 36 are abutted with the bed head. As shown in FIG. 1, faces 40 and 55 are abutted with the bed head on the opposite side to that of base 18 with brackets 49 and 62 being opposed and transversely displaced so as to be disposed either side of the bed head. Frame 34 is then retracted by telescopically collapsing the ends of beam 65 into respective ends 38 and 53 such that the opposite sides of bed head 25 are respectively received within openings 51 and 64 and then progressed into abutment with faces 50 and 63. After any minor height adjustment is affected, wheels 66 and 67 are turned to move the corresponding grub screws into a locked configuration for fixing frame 34 with respect to bed head 25. To remove frame 34 from bed head 25, the opposite steps are followed. In the event that any subsequent alignment changes are required, it is only necessary to loosen (and subsequently tighten) one or other of wheels 66 and 67. Accordingly, such adjustment is more easily able to be provided from either side of bed head 25.

System 1 also includes a mounting frame 70 that is illustrated in more detail in FIG. 5. Frame 70 includes two parallel transversely spaced apart coaxial tubular rectangular beams 71 and 72. Beam 71 extends substantially vertically from a closed top end 73 to an open bottom end 74. The beam includes a substantially transversely extending and vertical front face 75 and an opposite and parallel back face 76 that both extend between end 73 and the end 74. Faces 75 and 76 are joined by substantially longitudinal and vertical side faces 77 and 78. Face 77 includes a vertical rectangular slot 79 that is adjacent to face 75 and which extends from end 74 to the midpoint between end 73 and end 74.

Face 77 includes a generally circular aperture 80 that is disposed adjacent to end 73 and which is centred midway between faces 75 and 76.

Beam 72 extends substantially vertically from a closed top end 81 to an open bottom end 82. The beam includes a substantially transversely extending and vertical front face 83 and an opposite and parallel back face 84 that both extend between the top 81 and the open end 82. Faces 83 and 84 are joined by substantially longitudinal and vertical side faces 85 and 86. Face 85 includes a vertical rectangular slot 87 that is adjacent to face 83 and which extends from end 82 to the midpoint between end 81 and end 82.

Reflectors 15 and 16 are fixedly secured to faces 83 and 85 respectively and are disposed adjacent to end 81. Reflector 17 is fixedly secured to face 75 and is disposed adjacent to top 73. The reflectors 15, 16 and 17 and aperture 80 are centred in a common horizontal plane.

The reflectors are fixed to the associated faces by way of adhesive. However, in other embodiments, use is made of screws, bolts or other fixing means.

Faces 77 and 85 are opposed and are mirror images of each other. Moreover, in use, beams 71 and 72 are co-extending, in that end 73 and 81 fall substantively within a common horizontal plane, while end 74 and 82 fall within another common horizontal plane.

Frame 70 includes a third intermediate beam 88 having two opposite ends 89 and 90 which are fixedly mounted to faces 79 and 85 respectively. Beam 88 maintains beams 71 and 72 in a fixed parallel spaced apart relationship.

Receiver 7 and emitter 10 are collectively mounted within beam 71 adjacent to end 73 such that emitter 10 directs beam 13 through aperture 80 and toward reflector 16. Once the beam hits reflector 16 it is redirected toward aperture 80 and to receiver 7.

Frame 70, in use, is slidably mounted to end 20 of bed 2. This mounting is affected by initially manually aligning frame 70 such that ends 74 and 82 of beams 71 and 72 respectively are positioned above but adjacent to footboard 28. The frame is then lowered such that the opposite sides of footboard 28 are received within respective slots 79 and 87. The lowering of frame 70 continues until beam 88 is abutted with top 29 of footboard 28.

As schematically shown in FIG. 6, the emitter/receiver pairs 6 and 9, 7 and 10 and 8 and 11 are electrically connected to controller 44 by respective low voltage electrical cables 91. These cables establish both power and data linkages between the pairs and the controller.

In the other Figures, cables 91 are not shown for the sake of clarity. However, it will be understood that these cables are minimally exposed to inadvertent contact. In this embodiment, the cables extend inside one or more of the tubular beams and base 18. This reduces the ability of a user or other person to tamper or interfere with system 1.

This safety aspect of the preferred embodiment is enhanced through the use of a 12 Volt DC power supply (not shown in FIG. 6). Accordingly, the maximum voltage carried by cables 91 is 12 volts and, thereby, presents a very low risk of injury to a user of the bed even if the user is able to access the concealed cables. In other embodiments use is made of alternative voltages.

As reflectors 15, 16 and 17 are passive components there is no need to have power or data cabling provided to them. Accordingly, the only need for power and data at frame 70 is for the emitter and receiver pair formed by emitter 7 and receiver 10. This power and communication link is provided by a low voltage cable (not shown) having ends that terminate in respective connectors. In this embodiment, the connectors are both 3.5 mm stereo audio plugs. The emitter and receiver pair and controller 44 each include a 3.5 mm socket for complementary receiving respective ends of the plugs.

System 1 is able to be integrated into a medical staff-call system 100. By way of example, FIG. 6 illustrates system 100, which includes a central controller 101 and a plurality of medical staff actuators 102 that are linked to controller 101 for allowing a user of a bed associated with each actuator to remotely call for assistance. Controller 101 includes an alarm 103 for providing one or more visual and/or audible indications that assistance has been sought. In some embodiments, controller 101 is configured to recognise and distinguish between a plurality of different types of requests for assistance from the user. Moreover, controller 101 is able to actuate alarm 103 to provide different indications in response to those different types of calls. This allows medical staff to quickly and easily ascertain not only the location where assistance is sought, but also a general indication of the type of assistance that is required.

In this embodiment, controller 101 includes a separate channel or port for communicating with each actuator 102. However, in other embodiments, use is made of a single communication bus.

To facilitate the inclusion of system 1 within system 100, use is made of a port multiplier 104. This multiplier allows a simultaneous and parallel connection of controller 44 and an existing medical staff-call button 105 to controller 101.

Multiplier 104 is connected to controller 101, system 1 and actuator 105 by respective cables 106, 107 and 108. Each of the connections between the cables and multiplier 104 are different. This reduces the risk of incorrect connection of the cables and the resultant erroneous alarm signals that would arise. Preferably, also, each of cables 106, 107 and 108 include the same connectors at both ends. So for example, in this embodiment, cable 107 includes at each end respective 6.5 mm audio stereo plugs (not shown). Consequently, the input port for cable 107 to multiplier 104 is a complementary 6.5 mm audio stereo socket (not shown), and input port for cable 107 to controller 44 is a complementary 6.5 mm audio stereo socket (not shown).

In other embodiments, controller 44 is connected to a standalone audible and/or visible alarm (not shown). In these embodiments, controller 44 is preferably connected to a timer which enables and disables the system at pre-selected times.

Controller 44 is located within a prismatic plastic container 109 and includes a circuit configuration that is schematically shown in FIG. 7. The controller is connected to a 12 Volt DC supply 110 via a main isolating switch 111. In this embodiment, supply 110 is derived from the mains supply (not shown), while in other embodiments use is made of a low voltage supply such as that known to be ducted through hospital wards.

Controller 44 includes a plurality of interconnected components, such as normally open latching relay 112 and a normally open reed relay 113 that are located within container 109, and a normally open reset button 114 and an LED 115 that are mounted to container 109 and which are externally manually accessible. It will be appreciated that when any one of the beams 12, 13 and 14 are broken, LED 115 will be driven to emit light. This continues until a manual depression of button 114 occurs.

Cable 91 includes two power lines 116 and 117, and a data line 118. Lines 116 and 117 are, at one end, connected to supply 110 via controller 44. The other ends of these lines are connected with a normally open remote relay 119. It will be appreciated that system 1 includes three like relays 119, one for each of the emitter/receiver pairs.

The emitter/receiver pairs are provided with power from lines 116 and 117 via respective relays 119. Additionally, the pairs provide controller 44 with the movement signals along respective lines 118. The primary function of relays 119 is to buffer both the power supply to the respective pairs, and the signal from respective pairs.

It will be appreciated by a skilled addressee, particularly from the circuitry provided in FIG. 7, that controller 44 is responsive to the movement signals to generate an alarm signal in cable 107 that corresponds to an alarm signal that would be generated if system 1 were substituted by an actuator 105.

Moreover, multiplier 104 ensures that if any one of cables 107 or 108 includes an alarm signal, that system 100 will be responsive.

It will be appreciated that cable 107 includes in addition to wires 119, 120 and 121, a flexible plastics insulating sheathing (not shown) and a metal sheathing (not shown) for shielding the signals in the cable. In other embodiments use is made of different cables.

In use, system 1 will activate system 100 until an attendant resets system 1 by manually pushing button 114. This functionality is analogous to that provided by actuator 105, and operates in parallel.

Closing switch 111 activates the emitter/receiver pairs 6 and 9, 7 and 10 and 8 and 11. Each receiver 9, 10 and 11 includes an LED lamp (not shown) for indicating that the respective receiver is activated.

If a user of bed 2 attempts to leave the bed, it is extremely difficult for them to do so without entering and then passing through the field defined by beams 12, 13 and 14. That is, in attempting to progress from the bed the user is likely to break at least one of the beams. This is particularly so for elderly patients or those otherwise lacking mobility or who are partially mentally incapacitated. Accordingly, as the user crosses the periphery, one or more of beams 12, 13 and 14 is or are broken by the user. This results in relay 112 and relay 113 being powered and generating an alarm signal in cable 107. The LED 115, which is disposed across relay 112, indicates that system 1 alarm has been activated. That is, controller 44 acts as an interface between the emitter/receiver pairs and system 100 for engaging alarm 103 on system 100. The attending medical staff subsequently deactivate alarm 103 by pressing button 114.

Accordingly, system 1 provides an enhanced function to that of the button 105, but in conjunction with the existing infrastructure for that button.

System 1, in combination with some software modifications to system 100, allows the medical establishment in which bed 2 is placed to better manage the time and resources associated with providing care not only to the user of bed 2, but in the establishment as a whole. Particularly, one of the significant costs in providing care to patients is labour. This is exacerbated in circumstances where specialist care is required to be administered. System 1 allows system 100 to record time stamp data for each occurrence of the signal that indicated assistance was required. This time stamp data, in this embodiment, is sampled over a predetermined periods of typically a day, a week and a month. This provides information not only about the activities of the patient, but also of the resources required to care for that patient. For example, if a patient is showing a steady history of two movements from bed 2 per night, staffing levels are then able to be planned more accurately. However, if the number is trending upwardly, staffing is adjusted accordingly.

In some embodiments, the patient is levied a charge that is derived from the number of requests during a predetermined period to allow cost recovery of providing the resources to deal with those requests.

The time stamp data includes an identifier for the predetermined period and is gathered over a plurality of predetermined periods to allow the trends to be established. It is also possible to provide reports or other representations of the data to the patient's medical advisor.

Another embodiment of the invention, in the form of system 121 a, is shown in FIG. 9 where corresponding features are denoted by corresponding reference numerals.

In this embodiment, the three emitters 9, 10 and 11, three receivers 6, 7 and 8 and the reflector 15 are located at the foot end 20 of a bed 122 b. The two reflectors 16 and 17 are located at the head end 19 of the bed 2. The operation of system 121 a is similar to that of system 1 notwithstanding the different location of the components. That is, as a user (not shown) progresses from bed 122 b and breaks one or more of beams 11, 12 and 13, controller 44 is triggered to provide a signal that is preferably sent to a nurse-call system such as system 100.

The emitters 9, 10 and 11 and the receivers 6, 7 and 8 and the reflector 15 are mounted to a mounting frame 122 as best shown in FIG. 10. The mounting frame includes a square section tubular steel crossbar 123 extending transversely from a first end 124 to a second end 125. Two transversely spaced apart ‘Z’ clamps 126 and 127 are fixedly mounted to crossbar 123 between ends 124 and 125 for allowing frame 122 to the secured to foot end 20 of the bed 122 b by engaging a foot board (not shown) of the bed.

Two square section steel tubular arms 128 and 129 are slidably sleeved within the respective ends 124 and 125 of the crossbar 123 for movement between an operable configuration (as shown in FIG. 10) and a nested configuration. Crossbar 123 includes two cam locks (not shown) that, when in a locked configuration, are used to maintain arms 128 and 129 at desired relative transverse dispositions with respect to crossbar 123. When the cam locks are in an unlocked configuration, arms 128 and 129 are able to be transversely progressed toward the operable or the nested configuration.

Arms 128 and 129 have inner ends 132 and 133 that are nested within arm 123, outer ends 134 and 135 that extend outwardly in opposite directions from respective ends 124 and 125, and bottom faces 136 and 137 respectively. As best shown in FIG. 11 and FIG. 12, faces 136 and 137 each include a slot 138 and 139 for engaging with locating pins (not shown) to limit the transverse movement of arms 128 and 129 between the operable and the nested configuration. Moreover, as arms 128 and 129 are progressed into the operable configuration, the cam locks automatically move from the unlocked into the locked configuration for retaining the arms in the operable configuration until such time as the cam locks are progressed manually into the unlocked configuration. This operation allows arms 128 and 129 to be easily moved into the nested configuration, say, during the day and returned to the operable configuration at night. Moreover, the automatic locking in the operable configuration ensure that the alignment of the emitter and receiver pairs and the associated reflectors will be replicated notwithstanding the movement to and from the nested configuration. In this manner, system 122 a is able to be conveniently collapsed during the day and thereby minimising the risk of inadvertent contact with the user of care-givers, while allowing ease of return and alignment once the system is returned to the operable configuration.

Ends 134 and 135 support respective mounting brackets 140 and 141. As shown in FIG. 11, bracket 140 includes a front plate 142, and a back plate 143 that is opposed to and spaced apart from plate 142. Both plates are welded or otherwise fixedly attached to arm 136 and are joined by an intermediate abutment 144. The plates also include respective apertures 146 and 147 that are opposed and aligned.

Bracket 141 includes a front plate 148, a back plate 149 that is opposed to and spaced apart from plate 148. Both plates are welded or otherwise fixedly attached to arm 137 and are joined by an intermediate abutment 150. The plates also include respective apertures 152 and 153 that are opposed and aligned.

Brackets 140 and 141 interact respectively with two sensor box hinges 154 and 155 that are shown in FIGS. 13 and 14. Hinges 154 and 155 are respectively rotatably mounted to brackets 140 and 141 and each includes a spring-loaded catch (not shown) to maintain the bracket in position when operational.

As best shown in FIG. 13, hinge 154 includes a rectangular base 156 having a front face 157, aback face 158, side faces 159 and 160 and top face 161. Face 157 includes a rectangular slot 162 that extends through base 156. A steel panel 163 is mounted to face 159 and extends from a first end 164, past face 161, to a second end 165.

A plastic panel 166, that forms a lid for a sensor box 171, is, in use, abutted with panel 163 and has apertures that align with the corresponding apertures in panel 163.

A sensor box 171 has a front face 172, a back face 173, a top face 174, a bottom face 175, an end face 176 and an open end 177. It will be appreciated that face 177 is, in use, mounted to panel 166 such that the emitter and receiver pairs are housed within.

Emitter 9 and receiver 6 are rotatably mounted to a sensor post 178, which is mounted within sensor box 171. The sensor post extends through box 171 and is accessible for allowing manual adjustment of the beam used by emitter and receiver pair 6 and 9. That is, a user is able to centre emitter 9 and receiver 6 with reflector 16 through a 13 mm aperture 179 on front side 172 of box 171.

Emitter 10 and receiver 7 are mounted to panel 166 in line with apertures 180 and 181 in base 156 and panel 166 respectively.

Panel 166 is rotatably mounted to panel 163 to also allow for alignment of the light beams used by system 122 a.

It will be appreciated that hinge 154 is mounted to bracket 140 by placing 157 intermediate brackets 142 and 143 and inserting a hinge pin (not shown) that extends through apertures 147 and 147 and slot 162.

As best shown in FIG. 14, hinge 155 includes a rectangular base 182 having a front face 183, a back face (not shown), side faces 185 and 186 and top face 187. Face 183 includes a rectangular slot 188 that extends through base 182. A steel panel 189 is fixedly mounted to face 185 and extends from a first end 190, past the top face 187, to a second end 191. Panel 189 includes a first face 192 and a second opposite face 193 that is abutted with face 185.

A plastics panel, in the form of a sensor box lid 194, has a first side 195 and a second opposite side 196, is mounted to the second face 193 of the panel 189. A sensor box 197 has a front face 198, a back face 199, a top face 200, a bottom face 201, an end face 202 and an open end 203. As with box 172, box 197 has end 203 mounted to face 196 of lid 194 to appropriately house the associated electronic components.

Emitter 11 and receiver 8 are rotatably mounted to a sensor post 204 which is, in turn, mounted within box 197. Post 204 is accessible from outside box 197 for manual adjustment, in that is allows emitter 11 and receiver 8 to be centred with reflector 17 through a 13 mm aperture 205 on face 198 of box 197.

Two studs 206 and 207, each having a 4 mm diameter and a 12 mm length, are welded to face 192 of panel 189 to mount reflector 15.

In this embodiment, the arms 128 and 129 are extended approximately 100 mm from sides 21 and 22 of bed 122 b respectively by telescopically sliding arms 128 and 129 inside the crossbar 123. The arms are secured in position by cam locks 130 and 131 automatically progressing to the locked configuration. In other embodiments, the cam locks, or other locking devices, are manually progressed into the locked configuration to maintain the arms in the operable configuration.

When not in use, the sensor box hinges 154 and 155 are folded down toward each other and against respective abutments 144 and 150. The arms 128 and 129 are then progressed to the retracted or nested configuration to ensure that frame 122 is stored behind the foot end 20 of the bed 122 b.

Referring to FIG. 15 there is shown a mounting frame 350 which includes a crossbar 360 extending from a first end 370 to a second end 380. The crossbar 360 is constructed from 25 mm×25 mm×1.6 mm RHS and is sleeved within two clamping lugs 385 and 387. The mounting frame 350 includes two reflector arms 400 and 410 which are mounted at each end of the crossbar 370 and 380 respectively. The reflector arms are formed from 20 mm×20 mm×1.6 mm RHS sections that are slidably mounted inside crossbar 360. Two M6 nuts, 415 and 420 are welded at each respective end 370 and 380 of the crossbar 360 to carry setscrews (not shown) that lock reflector arms 400 and 410 in place. In this way, the reflectors arms can be slidably adjusted clear of any obstructions, such as pillows, and can then be locked into position using the setscrews (not shown).

Reflector arm 400 extends from a first end 415 to a second end 420. A post 425, in the form of a 50 mm×60 mm×1.6 mm metal plate, is mounted to the second end 420 of the arm 400. The post extends from a first end 427 to a second end 429. Two studs 430 and 431, being nominally 4 mm in diameter and 12 mm in length, are welded to a side 432 of the post 425 and are used to mount the reflector 20 to side 432.

Reflector arm 410 extends from a first end 450 to a second end 460. A post 470, in the form of a 50 mm×60 mm×1.6 mm metal plate, is mounted to the second end 460 of the arm 410. The post extends from a first end 475 to a second end 480. Two studs 490 and 492, of nominal 4 mm diameter and 12 mm length, are welded to a side 492 of the post 470 and are used to mount the reflector 17 to side 492.

Crossbar 360 includes a front side 510 and aback side 520. A plate 530 is mounted to front side 510 adjacent second end 380 of crossbar 360. The controller 101 is mounted to the plate 530.

In other embodiments of the invention, opposed emitter/receiver pairs are used rather than retroflective emitter/receiver pairs. Retroflective pairs are preferred for those applications where beam alignment over time is susceptible to disruption. For example, when the preferred embodiment is installed to a moveable hospital bed (not shown) there is an increased risk of unintended relative displacement between the various components within system 1 in response to inadvertent contact of the bed with other objects.

Another embodiment of the invention, in the form of a system 540, is shown in FIG. 25 where corresponding features are denoted by corresponding reference numerals.

In this embodiment infrared photoelectric proximity sensors are used in place of photoelectric sensors as described in the above embodiments. Using infrared photoelectric proximity sensors removes the need for reflectors such as reflectors 15, 16 and 17 used in the embodiments of FIGS. 1 and 9. It also allows system 540 to be used in applications where visible light from the photoelectric sensors is undesirable. Such applications include monitoring beds for users having dementia, as it is not uncommon for such user to be disturbed or otherwise alarmed by an unfamiliar beam of visible light.

In this embodiment, two spaced apart infrared photoelectric proximity sensors 542 and 544 are located at the head end 19 of a bed 546. A third infrared photoelectric proximity sensor 548 is located apart from sensors 542 and 544 at the foot end 20 of the bed 546. The sensors 542, 544 and 548 respectively produce beams 550, 552 and 554 around the perimeter of the bed 546. The operation of system 540 is similar to that of system 1 notwithstanding the different working of the components. That is, as a user (not shown) progresses from bed 546 and breaks one or more of beams 550, 552 and 554, an electronic controller 556 is triggered to provide a movement signal that is preferably sent to a nurse-call system, such as system 100, to generate an appropriate alarm signal. However, in other embodiments, audible and visual alarms, which are separate from the system 100, are triggered.

Sensor 542 is mounted to a mounting frame 558 as best shown in FIG. 27. The mounting frame includes a U-shaped clamp 560 for allowing selectively securing of frame 558 to bed head 25. In this embodiment, clamp 560 is disposed adjacent to edge 26 to provide the desired beam orientation. In other embodiments, however, clamp 560 is disposed otherwise with respect to bed head 25.

Clamp 560 includes a front plate 561 and two opposed side plates 563 that extend parallel to each other and normally away from respective opposite edges of plate 561. One of plates 563 includes a threaded aperture 565 for receiving a complementary grub screw and thumbwheel combination (not shown) that are moveable between a clamping configuration and an released configuration. In use, the grub screw and thumb wheel are initially disposed in the released configuration, and clamp 560 is progressed to receive bed head 25 between plates 563 and to bring the bed head into abutment with plate 561. Thereafter, the grub screw and thumb wheel are manually progressed to the clamping configuration to releasable secure clamp 560 to bed head 25.

Frame 558 includes a square section tubular steel crossbar 562 that extends transversely outwardly from a proximal end 566 that is secure to plate 561 and a distal end 568. Crossbar 562 receives a first end 567 of a right cylindrical tubular arm 564 for transverse telescopic movement between a retracted and a disengaged position. A second end 569 of arm 564 is fixedly engaged with a square section tubular steel crossbar 570. This crossbar has an engagement face 574 for supporting a substantially planar rectangular steel turntable 573 for rotation about an axis 571 that is intermediate the opposite transverse ends of the crossbar.

Turntable 573 fixedly engages sensor 542 for movement relative to clamp 560 and, in use, relative to bed 564.

Controller 556 is, in this embodiment, contained within a rigid plastics housing 575 that is fixedly mounted to a top end 576 of crossbar 562, and adjacent to clamp 560.

Crossbar 562 includes, adjacent to end 568, a reinforcing plate 572 having a threaded aperture for selectively receiving a thumbwheel (not shown) or other threaded locking device. Typically, clamp 560, in use, extends substantially vertically and, hence, arm 562 extends substantially horizontally. As end 567 is telescopically received within end 568, it is usual for axis 571 to be substantially vertical. However, in those embodiments where clamp 560 is disposed adjacent to edge 26, and that edge is considerably above mattress 31, arm 564 is rotated relative to arm 568 about a common horizontal transverse axis to provide the desired beam orientation with respect to bed 546. Once that desired orientation is achieved, the thumbwheel is adjusted to releaseably clamp against relative rotational and translational movement between arms 568 and 564. It is also possible to rotate turntable 573 about axis 571 to further refine the beam orientation. It will be appreciated that axis 571 will be other than substantially vertical following relative rotational movement between arms 572 and 564 from the position shown in FIG. 27.

In other embodiments, the thumbwheel is substituted by a clamp or other frictional lock.

In other embodiments, frame 558 is made substantially or entirely from plastics. More preferably, the frame is moulded from plastics.

Sensor 544 is secured, by way of a frame (not shown) to the opposite side of bed head 25 to that taken by frame 558. It will be appreciated that the frame for sensor 544 is a mirror image of that for sensor 542, and it omits controller 556.

Sensor 548 is mounted to a mounting frame 588 as best shown in FIG. 35.

In this embodiment, controller 556 includes a plurality of electronically interrelated active and passive components—including transistors—that are mounted on a common PCB, the circuit diagram of which is shown in FIG. 36. The use of this more sophisticated hardware—in comparison to that used in the other embodiments described above—allows additional functionality to be provided. For example, controller 556 includes a timer circuit for introducing a predetermined delay between the detection of a disturbance of the field, and the subsequent generation of a movement signal. If, during this predetermined delay, the disturbance to the field is abated, and the field returns to the steady state, controller 556 will not generate the movement signal. In this embodiment, where system 540 is intended for users who are prone to flail their limbs about during sleep, the inclusion of the timer reduces the risk of a false alarm signal being raised. That is, the alarm signal is intended to indicate the movement of the user from the bed, not the flailing about of the user's limbs. While in the earlier described embodiments the risk of such false alarms was obviated through beam positioning and orientation, the present embodiment includes the additional measures offered by the timer.

It will be understood by those skilled in the art that a timer, such as that described immediately above, is able to be included, where required, within the other embodiments as described in this specification.

In this embodiment, the predetermined delay is about 2 seconds. However, in other embodiments, alternative predetermined delays are used. It has been found that predetermined delays falling within the range of about 0 to 4 seconds accommodate the typical applications of embodiments of the invention. In appreciation of this, the inventor designed system 540 to include an external manual adjuster (not shown) that extends from the top of housing in which controller 556 is contained. This adjustor allows manual adjustment of the delay by the caregiver to best suit the user of the bed. This allows system 540 to be used sequentially for different users, whether on the same or different beds. The adjustor allows the predetermined delay to be set at anywhere between about 0 and five seconds. The adjustor includes a display to visually indicate to the caregiver the approximate delay to which the controller is set. Preferably, the display is in the form of markings or other indicia, while in other embodiments, the display is an electronically driven display, such as an alphanumeric display, a LCD or other similar device.

Controller 556 is housed within an electrically shielded housing to minimise electrical interference with and by other equipment that is used in hospitals, nursing homes and domestic residences.

System 540, including controller 556, is designed for low voltage operation to provide inherent safety for users and caregivers alike.

Sensors 542, 544 and 548 each utilise a source of electromagnetic radiation in the form of respective infrared light sources. Moreover, all of the sensors contain an emitter and a receiver (not shown) that are mounted side-by-side and contained within a single common plastics housing. In this embodiment the sensors are those manufactured by SICK AG and branded SENSICK and having the model designation WT34-V210. It will be appreciated that other models are able to be used to provide similar functionality.

The sensors 542, 544 and 548 are mounted to the bed such that the beams 550, 552 and 554 are about 150 mm above mattress 31 of the bed 546, as shown in detail in FIG. 26. Beams 550 and 552 also extend about 150 mm past the bed end 20 to ensure the beams extend along the whole length of the bed 548. This positioning and orientation of the field—as defined by beams 550, 552 and 554—has been found to provide excellent accuracy in generating movement signals. That is, the offset of the beams from the surface upon which the user is disposed assists in preventing movement signals being generated when the user is not actually attempting to or actually moving from the bed.

The embodiment of system 540 offers the further advantages of having few components and, as such, is able to be produced cost effectively. Additionally, system 540 provides an adjustable beam length to accommodate many different bed sizes.

Sensors 542, 544 and 548 have respective maximum sensing ranges that are adjustable to collectively define the field appropriately for a given bed, and to allow the sensors to be applied to different size beds, as required. The maximum sensing ranges of the sensors 542, 544 and 548 are respectively set accurately by adjusting the background suppression of the sensors. The sensors used in this embodiment include a calibrated adjusting screw (not shown) for allowing individual manual adjustment of the of the background suppression. The sensors also include a detection display, in the form of an LED (not shown), that is mounted to the housing of the sensor and which illuminates when the beam provided by the sensor is interrupted or broken.

In this embodiment, the location of the LED on the housing is such that the visible light produced is directed away from the bed. This minimises the intrusiveness of such light to the user. More preferably, the light produced by the LED is directed primarily upwardly to also minimise the intrusiveness of the system to those persons in adjacent beds in multi-bed rooms. However, the light provided by the LED, once triggered, is easily seen by a caregiver. This allows that caregiver to quickly and easily determine the beam that was broken by the user.

To adjust the sensors it is first turned on so that the respective beam is generated accordingly. The location of the beam is determined by the relevant person moving their hand or an instrument—such as, for example, a white sheet—across the general line-of-sight of the sensor to detect the beam. If the detection display illuminates immediately, it is apparent that the respective beam is broken. Accordingly, to complete the adjustment the person concerned adjusts the background suppression—and thereby focuses the beam—to a point near the end of the bed.

With the beam range set for the bed to which the sensor is mounted, the thumbwheel in aperture 561 is progressed to the released configuration to allow any required vertical adjustment of clamp 560 relative to bed head 25 such that the beam is about 150 mm above the surface upon which the user is to rest. Thereafter, the thumbwheel is progressed to the clamping configuration to releasable vertically locate clamp 560 relative to the bed.

The thumbwheel in aperture 572 is then moved to a released configuration and the sensor is adjusted transversely such that the beam is about 150 mm outside the edge of the bed. Once so disposed, the thumbwheel is moved into the clamping configuration. The final adjustment accommodated by frame 558 is to allow rotation of the sensor about a substantially horizontal axis to allow an inclination of the beam with respect to the surface of the bed upon which the user rests.

Sensors 542, 544 and 546 are contained within respective generally rectangular prism housings, each of which includes a rectangular face from which the beam emerges, and through which incoming signals are detected. The rectangular face has a long side and a short side, with the internal sensor and generator being disposed adjacent to each other and to a respective one of the short sides. In this embodiment, the long side of sensors 542 and 544 are disposed substantially horizontally as this has been found to minimise the attention they receive from users of the bed. For those users with certain mental illnesses or conditions, the horizontal orientation shown in FIG. 25 has been found to be less threatening.

In other embodiments, however, the long side of the sensor is mounted substantially vertically, or at an angle to the vertical.

Where use is made of sensors having generally prismatic housings, those housing have a depth, a height and a width. These characterisations, in the context of this specification, are measured as follows. The depth is parallel to the respective beams, while the height and width are both normal to those same beams. It has been found, in use, it is advantageous for those sensors mounted to the head of a bed to ensure that the height—that is the vertical dimension—is less than the width—that is, the horizontal dimension. It has also been found that for the sensor located at the foot of the bed the orientation is often less critical as the sensor itself is typically more obscured from the user by the bed itself and is therefore less likely to cause consternation or confusion of the user.

It will be appreciated that the illustrated system is advantageously applied to beds where the user, if allowed to venture from the bed unattended, will be at an unacceptable risk of injury or mishap. Moreover, this is achieved in a non-invasive and non-intrusive manner.

Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention can be embodied in many other forms. 

1-40. (canceled)
 41. A sensor assembly for a bed, the assembly including: a support member for mounting to the bed; at least one sensor support that extends between a proximal end that is mounted to the support member and a distal end, wherein the support is movable between an operable position and a stored position in which the distal end is respectively spaced apart from and adjacent to the member; and sensor equipment that is mounted at or adjacent to the distal end.
 42. A sensor assembly according to claim 41 wherein the support member is releaseably mounted to the bed.
 43. A sensor assembly according to claim 42 wherein the support member is clampingly mounted to the bed.
 44. A sensor assembly according to claim 43 wherein the assembly includes two sensor supports that are at or adjacent the ends of the member.
 45. A sensor assembly according to claim 44 wherein the distal ends of the respective supports progress toward each other as they are moved into the stored position.
 46. A sensor assembly according to claim 45 wherein the support is gravitationally biased into the operable position.
 47. A sensor assembly according to claim 46 wherein the member includes a locating formation, and the proximal end includes a mounting formation that inter-engages with the locating formation for guiding the movement between the operable and the stored positions.
 48. A sensor assembly according to claim 47 wherein the locating formation includes a pair of opposed flanges and a locating pin, and the mounting formation includes a slot for slideably receiving the pin.
 49. A sensor assembly according to claim 48 wherein during movement between the operable and stored positions, the locating formation and the mounting formation are relatively translated and rotated.
 50. A sensor assembly according to claim 49 wherein the translation and rotation are consecutive.
 51. A sensor assembly according to claim 50 wherein there is only a single translation and a single rotation.
 52. A sensor assembly according to claim 51 wherein the proximal end is slideably mounted to the member.
 53. A sensor assembly according to claim 52 wherein the member extends transversely, and the support is mounted to the member for relative slidable movement between the operable and the stored positions.
 54. A sensor assembly according to claim 53 wherein the member is tubular and the support is telescopically mounted within the member.
 55. A sensor assembly according to claim 54 wherein the sensor support includes an arm that is moveable between a nested and an extended configuration with respect to the support member in response to predetermined movement of the sensor support toward the retracted and operable positions respectively.
 56. A sensor assembly according to claim 55 wherein the sensor assembly includes a locking device that moves between a locked and an unlocked configuration wherein, in the locked configuration, the locking device maintains the arm in the extended position.
 57. A sensor assembly according to claim 56 wherein the locking device automatically moves to the locked configuration as the arm moves into the extended configuration.
 58. A sensor assembly claim 57 wherein the locking device is manually moved into the unlocked configuration.
 59. A method of mounting a sensor assembly to a bed, the method including: mounting a support member to the bed; providing at least one sensor support that extends between a proximal end that is mounted to the support member and a distal end, wherein the support is movable between an operable position and a stored position in which the distal end is respectively spaced apart from and adjacent to the member; and mounting sensor equipment at or adjacent to the distal end. 